Without a spectrum analyzer at the scene of the alleged interference, it's a guessing came. Could be anything/anyone.
and, if the source of the interference is a cell site, broadcast, or any licensed radio spectrum user who is operating within their emission mask, you and your neighbors are SOL.
Garage door openers, cordless phones, WiFi, Bluetooth, etc are all authorized under 47 CFR Part 15.5 The two main rules are:
§ 15.5
General conditions of operation.
(a) Persons operating intentional or unintentional radiators shall not be deemed to have any vested or recognizable right to continued use of any given frequency by virtue of prior registration or certification of equipment, or, for power line carrier systems, on the basis of prior notification of use pursuant to § 90.35(g) of this chapter.
(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.
(c) The operator of a radio frequency device shall be required to cease operating the device upon notification by a Commission representative that the device is causing harmful interference. Operation shall not resume until the condition causing the harmful interference has been corrected.
(d) Intentional radiators that produce Class B emissions (damped wave) are prohibited.
So, in other words, your garage door opener must accept interference which may render it inoperable. And it must not cause any harmful interference to any licensed radio spectrum user.
In plain English, part 15 is "where is, as-is" basis of radio spectrum use and the lowest on the totem pole.