What anticav units mostly suffer from, actually, is not bonus vs mounted but
reduced base strength.
I've written this before so I'll be brief, but there is a clear pattern in the game where units go up 10 strength per era. This is on a scale of
25/35/45/55/65/75/85 for the ancient to atomic/info (the last upgrades are sort of clumped together.)
There are some adjustments for each class too; namely, ranged units are 5

lower than the era standard, and have -10

compared to their

. (This makes them weaker on defense. Also ranged units were super OP in past games.)
Heavy cav have extra strength (+3-5) while light cav tends to have reduced strength.
The warrior and slinger seem to have a -5str attached because they are available turn 1.
Okay, where is this going: Ask yourself why pikes are at 41

instead of 45

. It doesn't make sense - pike and shot are at 55

. Spearman vs chariot is the same as if you had 45 pikes vs knights. It's not unbalanced there, why would it be here? I'm going to skip over the entire problem they had where pikes used to cost more than knights too.
Then we get to the modern era. The melee line almost
perfectly fits the trend,
except at infantry. Infantry and AT crew are at 70 instead of 75. This is why tanks are so dominant - the trend suggests a tank is actually right on target for strength. I strongly suspect infantry are weaker because there's no rifleman unit (but see than redcoats and gardes imperiale are at 65

, exactly 10 over muskets) and somehow they thought this would create balance. This odd deviation actually affects other units too, like machine guns (they should be 80

/70

.)
But while they boosted mech infantry early on from 80 to 85, back on trend, they never touched modern AT, who is stuck at just 80.
What they most desperately need to do is push pikes to 45

and AT crew/modern AT to 75

/85.

. Remember that +10 bonus vs mounted is a +50% multiplier. In civ5, anticav had a +50% multiple too. It's not the multiplier but the base unit; because those examples are so weak against everything, they won't survive to fight cav in the first place. They made a great backbone for unit strengths; they need only stick to it.
AFAIK, no. I mean they have redeploy as a tier 3 promo still but that's it.