I'm currently in year 2 spring on my savefile and used a few buffs before joining the fishing contest:
Fleeting Feet
Blessings of Luck
Fishing Buff
I tried fishing at different locations, because the game kept freezing at town square when the countdown hit "7/6 hours left". It also freezes when doing nothing in any other location after joining the contest.
After several crashes I figured out that I could avoid a crash, when using fast travel right before the countdown hits a full hour ( fast travel around "7:05 hours" to prevent" 7 hours "crash and so on).
I'm convinced that those buffs in combination with the festival is too much for my concole to handle.
------ 2nd attempt from older savefile -----
I replayed a few days and only chose the fishing buff this time.
Somehow the game froze at 9 am at the town square, even though I didn't join the fishing contest and was idle. 😭
So far I reloaded the day 10+ times and nothing seems to help. Restarting my switch didn't solve the problem either.