Friend has age inappropriate crush unsure how to word my response.

I made a new friend a few months ago and today she told me she has a crush! I was happy for her as when I first met her she was getting over a bad breakup. Until I found out how old her crush is. My friend is 25 almost 26 and her crush is newly 18…

I’m one of those people that see that as age inappropriate as when you’re 18 you’re not as mature as an adult is, you’re just finishing up school perhaps considering university, overall you’re in very different life stages.

Especially since she hasn’t been 18 for long…

I know technically they’re both adults but idk the age gap seems wrong for an 18 year old.

Anyways I know I need to tell her that I don’t think it’s appropriate for her to make a move but I can’t seem to find the words and was looking for any words of advice on how I could phrase this! Thank you all!