Filtering column based on matching conditions in another column

I am trying to perform a simple filtering using dplyr but it doesnt seem to work with what I want to do.

I want to filter a dataframe based on Time as an example when only if Time matches the category, then look at column Value.

example dataframe

df <- read.table(header = TRUE, text = "SubjectID Treatment Time Value
                A1 Amutant T0 5.3
                B0 Control T0 4.8
                A3 Amutant T3 4
                B1 Control T1 3
                B3 Control T3 6.5
                C2 Bmutant T2 2
                C1 Bmutant T1 3")

df %>% 
  group_by (Time) %>% 
  filter (Time == "T0") %>%
  filter (Value <5)

This seems not what I exactly want to get because I want to subset the whole row of those that match T0 values <5.

The results should be filtering out only those subjects with T0 higher than 5 but should not affect T1, T2, T3.

Thanks in advance!