First, if Microsoft used any of the Spegel code then it should provide proper attribution. A best practice is to put the LICENSE file in the root of project (both peerd and spegel do). But also, you need to put the license in the header of each file as a best practice. Like Microsoft did here https://github.com/Azure/peerd/blob/main/api/docs.go#L1

spegel did not follow best practices to put the copyright in the file itself: https://github.com/spegel-org/spegel/blob/main/internal/web/...

Ideally starting with something like this

// SPDX-License-Identifier: MIT