UK income tax for airdrops

Filling out my self assessment for the year and the HMRC guidance seems to suggest that you have to include airdrops as part of your income. Fair enough I thought.

Reading further into it though, it claims that income tax on your airdrops are based on 'fair market value of the tokens on the day you received them in GBP'..

Surely this cant be right?? If you receive a £1000 airdrop for example, and it drops in value over the course of a tax year while youre hodl'ing (lets say it goes down to £100 during a bear market correction), then theyre saying youd potentially owe more in tax than the actual tokens are worth??