That's a good thing. If their top engineers were leaving, that would be a bad thing. When management leaves, the engineers become more efficient.
That is an incredibly silly generalisation. Yeah some managers are shit and produce inefficiencies, but some managers are the opposite and contribute heavily to successes of projects. Just for fun I had a look at who left. Google's AI results showed 4 people leaving the vehicle division:
1x Chemical Engineer with a history of manufacturing optimisation.
1x Aerospace engineer with a post grad study related to manufacturing.
1x Mechanical engineer with a masters in manufacturing systems (also this guy, Emmanuel Lamacchia, lead multiple wildly successful programs at Tesla including the Model Y program which is Tesla's best selling product)
1x Electrical Engineer with a masters in electrical design.
So yeah let's celebrate getting rid of those "managers" who were holding back the engineers.
On the flip side we just lost a high profile manager where I work, a veteran accountant, with an MBA, and a history working for nothing but consultants. Yeah we were all very fucking happy he's gone.
Don't generalise.