Democrats are not going to lose any US Senate seats in the 2022 US Senate Election cycle.

In 2022 there are not any Democratic held US Senate seats that are in the Safe/Likely Republican column like AL-2020,IN/MO/ND-2018.
The Democratic held US Senate seats up in 2022 that is not safe is-
GA(Warnock-D) if he wins the 2020 Special US Senate Election. Warnock-D will win re-election to a full 6 year 1st term in 2022.
AZ(Kelly-D) will win re-election to a full 6 year 1st term in 2022 even against Ducey-R.
NH(Hassan-D) wins re-election against Sununu-R and/or Ayotte-R.
NV(Cortez Masto-D) wins re-election against Sandoval-R.
CO(Bennet-D) wins re-election by a double digit margin similar to the Hickenlooper-D vs Gardner-R 2020 race.
CA,CT,HI,IL,MD,NY,OR,VT,and WA are safe Democratic states at the Presidential Level.
On the Republican side- the vulnerable US Senate seats up in 2022 are
FL(Rubio-R)
IA(OPEN Grassley-R)
NC(OPEN Burr-R)
OH(Portman-R)
PA(Toomey-R)
WI(OPEN Johnson-R)

NC,PA,and WI will be the Republican held US Senate seats up in 2022 that the Democrats will win.