I'm unsure exactly how templates are picked and in what order in this module, but when specifying a list of instances they're converted into a Set, which alphabetises them and means that the order is broken. Eg, if passed an array:

instance_types = ["z1d.large", "r5a.large", "r5.large", "r5ad.large", "r5n.large", "t3.xlarge", "m5a.xlarge", "t2.xlarge", "m5.xlarge", "m4.xlarge"]

It will be converted into a Set, which becomes:

instance_types = [ "m4.xlarge", "m5.xlarge", "m5a.xlarge", "r5.large", "r5a.large", "r5ad.large", "r5n.large", "t2.xlarge", "t3.xlarge", "z1d.large" ]

This means that the spot instances that are spawning are preferring m4.xlarge rather than the z1d.large that I'd prefer.