I would recommend having your deck checked before the event starts. You can potentially be penalized for marked cards because of foil curling.
#Foils in deck
royal condor
Anecdotally, I've had a lot of success using Dragon Shield sealable inners and...this is weird...breathing warm humid air into the inner before sealing it lol
Then I let the deck sit under something heavy overnight, and I try to keep my decks packed tightly in their boxes.
vocal cave
dragon shield sealable inners work well for me, can't speak to the breathing thing though. Specific strategies will vary depending on your area's humidity
narrow kraken
Your obligation is a player is to ensure that your cards aren't marked, be it from foil curling or otherwise. There is no issue with having unmarked foils or non-foils.
storm marlin
If you want to check for yourself, some quick things to try is looking at your deck from the sleeve opening side and seeing if you can tell cards apart, if you can see if you can still pick them out after shuffling
wild talon
If you think it is questionable if it is marked or not, it probably is. I would recommend finding non foil copies just in case, if you are able to.
oblique cradle
Also a quick reminder: while it doesn't hurt to have a judge double check your foils before the event, the foils being fine at the start of the day does not mean they'll be fine later. They can and often do curl more as the day goes on
austere pasture
As a general note; the only way a deck can get cleared as acceptable for an event, is during that same event. So even if you are checked and cleared during an event on Friday as an example, we can and may check you in different event on Saturday.