New Home: daily, random, multiple AFCI breakers tripping
Your grounds are certainly not the problem.  More grounding is better, and an Ufer ground tied into the foundation is the best there is.
19 AFCI breakers, eh? And people wonder why we say &quot;Go BIG&quot; when buying service panels. They're all on the left side, but that doesn't indicate anything special - for instance they're not all on the same &quot;leg&quot;.  If every other row of breakers was tripping and not the others, that would be interesting, but I'm sure you would have mentioned that.
A marvel of compact tech
A semi-modern &quot;AFCI&quot; breaker has 3 detection modes of interest to us today.

Overcurrent -- you are pulling significantly more than 20 amps (which itself has 2 modes, but that's irrelevant here).
Arc Fault - a small computer with a digital signal processor is listening to the electric line, for that characteristic sound of arcing - that &quot;crinkle crunch&quot; sound you get when plugging in headphones, or headphones with a bad connection, or hooking up speakers with the amplifier turned on.  This is listening for series arc faults (inline with the load on hot or neutral), or a parallel (shorting) arc fault between hot and neutral.
Ground fault - this is a weakened form of &quot;GFCI&quot;, closer to a &quot;GFPE&quot; or a European &quot;RCD&quot;.  Not good enough for human safety, but an effective way to detect parallel (shorting) arc faults hot-ground or neutral-ground, e.g. a hot wire sparking to a ground wire. Those are also ground faults.

Square D's &quot;TIME SAVER Diagnostics&quot;, available on breakers with a white or purple TEST button, will store the cause of the last trip: immediate trip means a ground-fault (meaning the AFCI's weak GFCI-section detected a hot-ground or neutral-ground fault).  A 2-second delayed trip means the computer detected the &quot;sounds on the wire&quot; of an arc fault.  A 5-second delay means, well, the ground- and arc-fault sections don't know why it tripped, so it must be the dumb old overcurrent breaker.
In the panel, everyone can hear you scream
The nature of the overcurrent and ground-fault tripping means that they can only trip for problems on the &quot;Load&quot; side of the device.
However, the &quot;computer, listening&quot; has a side-effect: It's listening to the &quot;Load&quot; side of the breaker, but the circuit breaker has very low impedance across it, and no noise filtering.  As such, the computer can &quot;hear&quot; arc faults on the &quot;Line&quot; side of the breaker, i.e. the panel's main bus.   An AFCI trip can occur from other circuits having an arc fault.
It's probably one thing
And I think that's exactly what's happening to you.  One of your circuits is arc-faulting,  and the other circuits are &quot;hearing it&quot; sufficiently to trip them.
It sounds like you can guess which circuit that is.
So where do we look for arc faults on a particular circuit?  Start at terminations of wires - breaker lugs, terminal screws, wire nuts - any end of any wire can be the source of the problem.  I would say replacing all the heat pump components is an expensive way to re-torque connections... but suffice it to say, any connections disturbed by this overhaul can be excluded since they've been re-torqued.
So I would focus on the connections which were not disturbed by that recent work, e.g. those on the breaker or neutral bar, or any intermediate splices.
It could be in the machine, but if the machine has been replaced, that would be surprising.
The last and remotest possibility is a broken wire - again typically that is near a termination, but it's not common at all.  It could also be a nail driven into a cable.