Very Saw Tooth Uplink SNR in cnM graphs

Don’t know if this is a bug in our cnM ( on prem v3.1.0-r1) or a problem with the AP/s . We only have 1 tower that still has 900Mhz 450i on it , 7 APs and almost every single CPE on every AP looks like this in the graphs. Only a few don’t, the ones that don’t are just a flat line, no changes at all and the ones with flat lines vs the ones with sawtooth don’t seem to correlate to good / bad SNR/RSSI/Quality no rhyme or reason to it. cnM glitch ? AP graphs look normal, no cpe’s dropping, not sure what to make of it.