how to check the proportional assumption based on the partial dependence survival curve

[wymin576]

hello sir,
I want to check the proportional assumption based on the partial dependence survival curve. i plot three survival curves stratified time.
the R code is as follows,

rm(list=ls())
library(randomForestSRC)
library(ggRandomForests)

data(pbc, package = "randomForestSRC") 
pbc.obj <- rfsrc(Surv(days, status) ~ ., pbc)

gg_md <- gg_minimal_depth(var.select(pbc.obj))

plot.variable(pbc.obj,surv.type = "surv",
              xvar.names = gg_md$topvars,
              days = 1800)
plot.variable(pbc.obj,surv.type = "surv",
              xvar.names = gg_md$topvars, 
              days = 2400)
plot.variable(pbc.obj,surv.type = "surv",
              xvar.names = gg_md$topvars, 
              days = 3600)

I know the hazard responses are not proportional as time progresses. however, I don't know how to prove my opinion.
can you explain the output and check the assumption?
Any help is appreciated!
best wishes