Home Inspector reported two 20 amp breakers not allowed in panel per manufacturer?
One throw too far

Your meter-main was designed to use a set of smaller sub-main disconnects instead of a single main disconnecting means, in accordance with NEC 230.71:


  230.71 Maximum Number of Disconnects.
  
  (A) General. The service disconnecting means for each
  service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No.1,
  3, 4, or 5, shall consist of not more than six switches or sets
  of circuit breakers, or a combination of not more than six
  switches and sets of circuit breakers, mounted in a single
  enclosure, in a group of separate enclosures, or in or on a
  switchboard or in switchgear. There shall be not more than
  six sets of disconnects per service grouped in any one location.
  
  For the purpose of this section, disconnecting means
  installed as part of listed equipment and used solely for the
  following shall not be considered a service disconnecting
  means:
  
  (1) Power monitoring equipment 
  
  (2) Surge-protective device(s) 
  
  (3) Control circuit of the ground-fault protection system
  
  (4) Power-operable service disconnecting means
  
  (B) Single-Pole Units. Two or three single-pole switches
  or breakers, capable of individual operation, shall be permitted on multiwire circuits, one pole for each ungrounded
  conductor, as one multipole disconnect, provided they are
  equipped with identified handle ties or a master handle to
  disconnect all conductors of the service with no more than
  six operations of the hand.


However, the pair of single pole breakers in the lower-right that the inspector complained about means that you need 7 breaker throws to turn all the power off, which is one too many.

Evict the aliens!

Furthermore, the culprit breakers are a violation by themselves as they are GE THQLs, which are not listed to go in an Eaton BR panel.  At this point, you might as well get a BR220 from the nearest supplier and have it slapped in in place of the culprits, killing two violations with one fix.

And yes, a two pole breaker can feed two completely separate 110V circuits

There is nothing in the NEC that prohibits a two pole breaker from feeding two independent branch circuits from the opposite legs it provides.