I am skeptical that this fungus absorbs radiation significantly more than the equivalent amount of water would. The paper [1] isn't very clear about possible inaccuracies in the results and I don't understand why this experiment hasn't been repeated down on Earth. The mass attenuation coefficient of the fungus is 0.234 cm^2/g at 100MeV whereas water is 0.0166 cm^2/g according to this paper [2].
[1] https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1....
[2] https://apps.dtic.mil/dtic/tr/fulltext/u2/a278139.pdf
Edit: I made a mistake in this comment, see child comment for correction.