It's all about Rare Land Cycles
This all started when Fetch lands were first reprinted in Zendikar Rising Expeditions and later again in Modern Horizons 2. These are very sought after lands and a staple in most formats where the cards are legal. The lands in your deck or Mana Base are probably the most important part of your deck. It is all well and good having the best cards in the current meta available to you or a card that can win the game there and then. But if you don't have the right mana to play the card then it's basically a dead card in your hand.
We understand why Wizards of the Coast are wanting to reprint as many lands back in circulation as they can. This makes supply high and more affordable for everyone who wants to play them. There always has to be a trade off between value and accessibility, but having a few more available can only help the game.
The first announcement of the year where the rare land cycles were coming back was in Unfinity, this is the latest Un- set which was due to be released in April but has been delayed until later this year. The lands being reprinted in this set are the Shock lands from Guilds of Ravnica and Ravnica Allegiance. These are dual lands that enter the battlefield tapped unless you pay 2 life, hence the term 'Shock' lands.
These Ravnica lands are still desirable and are still holding good value even though there is a known reprint coming at some point later this year. These cards remain amongst the most expensive cards in these sets and there are only a couple of other cards that compete for those top spots. These lands are going to be highly desirable when reprinted and this could explain why the values are still high, albeit they have come down a bit since the reprint was announced.
The 5 shock lands in Ravnica Allegiance are in the top 6 of the top value cards, only being beaten by Smothering Tithe, which is understandable. The cheapest (Stomping Ground) land can be picked up for about £7ish. This almost mirrors Guilds of Ravnica with the lands in that set being 5 of the top 6. This time it is Assassin's Trophy that gets in the middle of them. Temple Garden is the cheapest land in this set and these can be bought for around £6.50-7.
The second Rare land cycle announcement was in Streets of New Capenna, which comes out the end of April. This set is based around 5 rival crime families, each family is connected to 3 mana colours. This is not a re-print as such but more of a completing the current cycle of lands. However. Streets of New Capenna is getting the second half of the Triome cycle of lands from Ikoria, Lair of Behemoths. They aren't called Triomes in Streets of New Capenna but they function in exactly the same way.
These lands enter the battlefield tapped but they are tri lands rather than duel lands. These cards are great for mana fixing or for those 3 or more colour decks. Just like the Ravnica lands, all 5 of the Ikoria Triomes are in the top 7 highest value cards from the set. With the cheapest Triome being about £7-8. These are also highly desirable lands and this is what has kept the price so high. Since these lands are not getting a reprint but the cycle is being completed this is not going to effect the price of the Triomes but give a guide as to where the Streets of New Capenna will be in terms of price.
The most recent announcement from Magic the Gathering is that Commander Legends Dungeons and Dragons Battle for Baldur's Gate (yes, that is a really long title) will have the rare land cycle from Battlebond. Battlebond was a set designed for two-headed dragon but these lands see a lot of Commander play as the lands were designed for a multiplayer format. Most other Magic the Gathering formats are 1 vs 1. These Battlebond lands are duel lands that enter the battlefield tapped unless you have 2 or more opponents.
These lands are not in the top 5, barely making it into the top 10 of value cards in Battlebond but there are a lot of monster cards in Battlebond that hold higher value than these lands. But you are looking at paying about £10 for the cheapest of these lands (Spire Garden) but it does look like the prices have taken a little dip on the new announcement.
Looking at the value of these cards it is clear why they need a reprint. If you are building a deck on a budget then clearly these cards are unlikely to be an option for you. If you were to build a 3 colour deck and use a Triome and a couple of shock and Battlebond lands. For those 5 cards you'd be looking at spending £41, if you want a playset of these cards then you're looking at 4 times that.