That's a year and a half of social and mental development that our kids are missing out on. Remember how kids are always a bit wilder in the first couple weeks of school after not seeing each other all summer? Multiply that by fifteen for the amount of time that some haven't seen each other, and you get close to it.
It's going to take time - literally YEARS - for our kids to readjust to a school environment. Even if your kids were "on campus" last year, virtually NO ONE had a "normal year" with distancing, class sizes, and disruptions. Your 7th graders are acting like fifth graders because that's what they were the last time they were all together.
And it's everywhere. Every teacher board I read, people are complaining about it. The only solution is making sure you are implementing your SEL strategies and keeping firm expectations for conduct. This will NOT be fixed in a day, a week, or a month. We have a year and a half of conditioning to bring kids out of - your seventh graders may not act like what are "normal" students even until their junior or senior years of high school.
Teach the kids where they are, not where they should be, and work from there.