I suspect this isn't even remotely accurate. What exactly counts as BTGs is a separate discussion. For example, in theory every M-R brigade and regiment can form 3 BTGs so an army like the 58th with two M-R divisions and two brigades can theoretically produce (assuming two regiments per division which is the norm these days) 18 BTGs. However they also have tank units, so some armored BTGs (tank btln+MR coy) are to be expected. At maximum it can probably put out more like 20-22 BTGs. Now take the 8th Army which has two M-R divisions, but one of them is the experimental "heavy" division ORBAT with two tank and two M-R rgts and the other with just two M-R rgts. For M-R units we can expect 12 BTGs, but with the armored units, it's more like 16-18. Then again the 49th Army has 3 brigades, so armored and M-R it's at most 12 BTGs. So at maximum we are well above the 130 BTGs divided by 11 armies. On the flip side, Russia prefers to use contract soldiers for actual combat, so how many of those units are completely contract, including junior enlisted? This is unclear. If they're moving contract-only units, they're certainly not moving 9/11 armies. They're moving more like ~1/3rd to 1/2 of that. I'm not sure where the number of 130 BTGs comes from, but the whole thing looks like really fuzzy math. And some of the units arriving in Belarus from East MD appear to include conscripts, so...
100 BTGs would equal, in my math, to more like ~4 armies if we include airborne which would form BTGs of their own, and would certainly participate, but don't report directly to Combined Arms Armies.
On a side note, in addition to 12 (not 11) armies (1st and 2nd Tank Armies, 5th, 6th, 8th, 20th, 29th, 35th, 36th, 41st, 49th, 58th Combined Arms Armies) there are also 4 Army Corps (11th,14th, 22nd, 68th,)which are the Navy/Coastal Troops combined commands for ground forces in their area. They're mostly (the 14th only has two Arctic bdes) comparable to a combined arms army, but with fewer support elements (often lacking the artillery bde, or the air defense bde which is often replaced by a much smaller and weaker air defense rgt, often lacking engineers and logistics units). There are also 4 divisions and iirc 3 bdes of VDV which combined are well above any single army, and don't report to any of them. So all in all even if 9 armies were deploying to the border of Ukraine a more accurate picture would be 9/17 or 9/18.