It's awesome that you're donating to Lemmy, but we're likely to see another spike in signups at the end of the month, and it might be smarter to let some of the donated funds roll over into the next month. If people only do one-off donations, donating to Lemmy before you know if your next month's bill will be covered might put you in a tight spot.
If you're going for transparency, OpenCollective might also be an option.