Russian artillery around Bakhmut has been getting devastated this week. The question now is whether or not those experienced crews have been getting killed as well. Russia has TONS of artillery, but they're slowly burning through their best stuff and, presumably their best crews...
Meanwhile, despite Russia destroying about1/3 of the 150+ M777 Howitzers that USA, Canada and Australia originally sent Ukraine, the USA just announced that an undisclosed number of additional M777s will be sent over. It's speculated that the number is roughly 30, essentially replenishing the majority of the ones lost. Furthermore, the 32 AS-90, 155mm self-propelled howitzers that Britain pledged, have just recently arrived, along with 18 M109A6 Paladins pledged by the USA and the 19 CAESARs pledged by Denmark. Similarly, Germany announced that 18 of the 100 Panzerhaubitze 2000 self-propelled howtizers that Ukraine ordered in 2022, will be delivered "imminently". The 8, Swedish pledged 155mm Archer howitzers are also on route, as soon as training is completed.
As Ukraine's artillery capability takes a big jump forward, with the delivery of some of the finest systems in the world, Russia's artillery is taking an absolute beating on the flanks of Bakhmut. Even more importantly, extremely hard to replace crews, with tons of experience and being liquidated.
The West needs to keep the artillery coming. The following have been ordered / committed, but many have yet to fully arrive in Ukraine... The sooner, the better.
100x 155mm, Panzerhaubitze 2000, self-propelled howitzers (Germany)
30x 152mm DANA M2, self-propelled howitzers (Czech Republic)
54x 155mm KRAB, self-propelled howitzers (Poland)
24x 155mm SHKH ZUZANA 2, self-propelled howitzers (Slovakia)
8x 155mm ARCHER, self-propelled howitzers (Sweden)
24x 120mm M120 RAK, self-propelled mortars (Poland)
I think a more realistic explanation is that they realized that Russian aircraft were flying carelessly through the Bryansk region, feeling safe. They then set up an air defense system close to the border, but kept it offline until they were ready to execute the operation. They then turned it online, used its long range RADAR to track aircraft over Russia and started picking then off before Russia knew what's up. 
Macron promised a new military aid package for Ukraine. In typical French style, not all details of the package were made public, but one component of the package was. France promised to send more AMX-10RC tank destroying infantry fighting vehicles, in sufficient quantities to equip several battalions. I don't think 50 units would be out of the question given how many are needed to form a battalion.
and Rishi Sunak. The Brits also promised a new military aid package to Ukraine, containing hundreds of aerial attack drones of an unspecified type (200km range), as well as hundreds of additional air defense missiles to help replenish Ukraine's stocks. Also, they confirmed that Britain will host a training plan for Ukrainian pilots, beginning this summer. The program is aimed at re-training experienced jet pilots to fly the F-16.
