Some people who are 25 are interested in some people who are 20. If you are interested in them too, then it's a match! Some people call a relationship where one partner is older an "age-gap" relationship. Online communities fetishize, stigmatize, promote, discourage... etc. positive and negative attitudes toward it. There are often real risks present in those relationships that do not exist in others. There are often very real benefits in "age-gap" relationships that do not exist in others.
They have been historically very common especially amongst the wealthier classes. Most commonly the man is older, but there are cases of significantly older women too. The most common benefits for the younger person are: stability, access to new social groups, money, mentorship/wisdom, security, and if they have a sexual preference for older partners then fulfillment in that area too.
The most common benefits for the older partner are: opportunity to be generous with their money, opportunity to teach/mentor a lover, depending on what social group they are in it may increase their status, if the woman is of healthy child bearing age while other women may not be that is a benefit, and if they have a sexual preference/increased desire for a younger partner, then fulfillment in that area too
It's an honestly reasonable perspective to be opposed to power imbalances. Focusing in on the opportunity for a power imbalance to become abusive or "unfair" to others who may not have that power. Shorter men complaining that tall men take "all the women" Older women complaining that younger women "take all the men" Rich/poor, strong/weak, etc..
These days in the college educated liberal lower-middle class (Which the yik yak platform caters too mostly) you'll find much less support and much more rejection of "age-gap" relationships I personally think that the reason it's so often rejected is that this social caste is actually opposed to imbalances in power. There is a lot of rejection of "stronger man/weaker woman", "older man/younger woman", "taller man/shorter woman" .... etc