When you’re switching cell membrane types, you’re shown all the bonuses and drawbacks of a different cell membrane, in terms of the difference between current membrane and the one you’re considering. This oddly doesn’t apply if you’re switching between Cellulose and Chitin. If you have one of these, and look at the other, the other displays the +40% to its resistance (either physical or toxin damage), but doesn’t display the -40% to your membrane’s resistance (toxin or physical damage, respectively). This only applies to these two membranes, all others display correctly.
Oh, there’s actually another issue. All the stats of a membrane normally display as 0% improvement when you are using that membrane. When you switch to Cellulose or Chitin from another membrane, the four stats of those display as 0%, as normal. When you switch to Cellulose or Chitin from the other membrane in that pair, it only displays the resistance stat, as 0%.
I can confirm, opened a bug:
Thanks for the report.