Altitude instability with TfMini

Hello, does any one know why I get instability
of altitude after a while after converging (I use Tfmini for hgt) in this log https://review.px4.io/plot_app?log=b585ff8c-5575-4e63-aa6b-a76fd328bcd8 (sensor on TELEM1) same here also but with sensor on TELEM2 https://review.px4.io/plot_app?log=c1177425-340f-479c-8502-cdc653e23a91