cherry-pick #7557 to v1.66.x branch

[dfawley]

RELEASE NOTES: none

[codecov]

Codecov Report

Attention: Patch coverage is 75.86207% with 7 lines in your changes missing coverage. Please review.

Project coverage is 81.87%. Comparing base (62baa5f) to head (e1cba78).
Report is 1 commits behind head on v1.66.x.

Files	Patch %	Lines
encoding/proto/proto.go	72.72%	4 Missing and 2 partials ⚠️
codec.go	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           v1.66.x    #7564      +/-   ##
===========================================
- Coverage    81.89%   81.87%   -0.03%     
===========================================
  Files          362      361       -1     
  Lines        27865    27849      -16     
===========================================
- Hits         22820    22800      -20     
- Misses        3843     3854      +11     
+ Partials      1202     1195       -7     

Files	Coverage Δ
encoding/encoding.go	56.25% <100.00%> (-17.09%)	⬇️
encoding/encoding_v2.go	60.00% <100.00%> (+4.44%)	⬆️
codec.go	10.52% <50.00%> (-72.09%)	⬇️
encoding/proto/proto.go	66.66% <72.72%> (ø)

... and 17 files with indirect coverage changes