Tps starts slowly going down

We have a survival Minecraft server but its recently been lagging a lot. i do command blocking on the server but i've already tried turning all of it off and checking but it doesn't work. when we join the server it starts at 20 tps but within 1-5 minutes it will go down to 6. i've also tried all the lag fixing options that aternos provided.

I've already seen it, it didn't help

paper

also its ok i fixed it