Uhh in your title you’re talking about fucking but in the comments everyone is talking about dating.
There are issues with age gaps in dating/long term relationships. But if it’s just sex then it’s just sex. A 19 year old can consent to sex, and it doesn’t really matter if your partner is older because you’re not gonna have a long term relationship with them and you’re only gonna interact with them for one day.
If you don’t like the dating apps don’t use them. They’re not creating any more problems. They haven’t taken anything away from meeting people in real life.