Sources indicate that corporate-owned Leica Stores (company-operated flagships, as opposed to independent authorized dealers) are now directing their third-party accessory offerings toward a curated list of premium brands only. The approved brands reportedly include:
Leica Camera AG has not issued a public press release or official statement confirming this new policy, so this remains just another rumor.
Previous coverage of various Leica accessories can be found here:
Squarehood released several new lens hoods for M-mount lenses
FieldMade released new Leica stealth kits (blackout decals for Leica cameras)