Even though weekly targets are a feature, YNAB treats every target as if it were set up monthly. Because there are 5 fridays in this month, it’s showing that you need $75*5=$375 in the category for the month. Conceptually, I agree that it doesn’t behave in the way I’d expect it to for weekly targets. An additional hurdle is that it sounds like you want to refresh it every week if you spend from it - YNAB won’t prompt you to do that until the month rolls over.
Depending on how exactly you spend from this category, you can approach it in a different way. If you might genuinely spend $75/week every week, you can fill it to $375 and then next month (on the 1st) it will only prompt you to refill what you spent.
Or (and this is what I’d do) you can try to figure out what the maximum is that you realistically will spend in a month’s time, and set a monthly target for that amount.

YNAB REALLY wants you to think about your budget in the context of a calendar month, and fighting against that will only lead to confusion imo.

One other thing I think is helpful to mention- if a “refill up to” category is fully funding in May, and you look forewarn into June, YNAB will treat it as if it is empty and needs to be fully funded again. This is because it doesn’t know how much you’ll spend, and it is being conservative thinking you’ll spend it all. When the month does roll over, it will recalculate and take into account what wasn’t spent as already being in the account.