Evolution doesn’t work this way. Everything that happens to an organism past the standard age range of reproduction has 0 effect on natural selection. There is no system affecting “graceful decline” of body systems in some protective way for things that happen past 35 in women and maybe 45 in men.
But yes, as a HRT user myself (age 38), I do see it as replacing the fluids in my car to make it operate like when it was peak tuned at age 22.
That is absolutely not true. Even genetic variants from your father that are not inherited by you still influence your chances of survival and how likely you are to pass your genes to an offspring. Imagine your dad has a rare genetic variant, which you don't inherit, that means he is likely to be dead by age 50. Your fitness will be lower as you will lack a father during your childhood.
See this famous study: The nature of nurture: Effects of parental genotypes. Science, 359, 424-428 (2018). doi:10.1126/science.aan6877. The summary literally states:
"Genetic variants in parents may affect the fitness of their offspring, even if the child does not carry the allele. This indirect effect is referred to as genetic nurture. Kong et al. used data from genome-wide association studies of educational attainment to construct polygenic scores for parents that only considered the nontransmitted alleles."
What are your tested free-T levels after HRT? 500, 800, 1000? Age 38: That is pretty early, in my experience, unless you are using it as "HET" (hormone enhancement therapy) for bodybuilding -- basically, medical doctor-approved anabolic steroids.
But yes, as a HRT user myself (age 38), I do see it as replacing the fluids in my car to make it operate like when it was peak tuned at age 22.