To check, use a caliper to measure the thickness of the top and bottom acrylic base plates.
If they are in spec (8mm or slightly thicker) then do not perform this modification - your frame issues are elsewhere.
If your base or top acrylic plates are thinner (for example, in my G2S the base plate was 8mm, but the top plate was 7mm), you will be able to feel the end of the smooth rod slightly protruding through the acrylic, instead of inset, as required to stiffen the frame.
To resolve this issue, remove the suspect acrylic plate, and replace the single M8x1mm washers on the smooth rod ends with either two M8x1mm washers, or a single US 5/16th" x 1/16th" (approx 8mm x 1.5mm) washer. Note that all of the washers for the smooth rod ends must be identical.
Before:

After installing 1.5mm washer:
