If you run a Facebook business page, you shouldn't neglect your social media presence during the pandemic closures... or ever, really. There are two major reasons for this.
Facebook and Instagram both look at your posting consistency and quality, and adjust your place in the ever-elusive algorithm accordingly. It's best to post 3-7 times per week on Facebook, ideally once per day, but no more than twice per day unless you have a HUGE following with tens or hundreds of thousands of followers.
Depending on your type of business, you should post on Instagram a couple of times per week. If you're primarily online, daily is ideal up to three times per day. Brick-and-mortars tend to do well with 2-4 posts per week. If you always post on Wed, Friday, and Sunday, stick to that schedule. If you post sporadically, your posts will rank lower, thus getting less visibility. If you suddenly drop your consistent schedule, FB and IG will pretty much drop you too. It's REALLY hard to dig out of this drop.
Top of Mind Awareness
Don't let your customers forget about you. Even if they can't use your services or buy your products right now, keep your place in their realm of awareness. Maybe it's not the time to push big sales if many folks in your region have lost their income, but you can shift your strategy a bit. Share self-care tips, cross-promote things that other businesses are doing, or share some of your personal stories. Let people get to know you - the owner - so they're eager to come back and support you. People like helping people.