while loop condition "suspicious behaviour"

Question

code works fine except I can't figure out the while loop condition works unexpectedly
as I know when we compare two values (x<y) loop should work as long as condition valid less and not equal but i have something else in the code below
def check_prime(prime_list, new_number):

if all(new_number%i!=0 for i in prime_list):
prime_list.append(new_number)
return new_number
else:
return 0
prime_numbers=[2,3]
counter_prime=len(prime_numbers)
new_number=3

while counter_prime <= 100:

counter_prime=len(prime_numbers)
new_number+=1

x=check_prime(prime_numbers,new_number)

if (x !=0) and (x not in prime_numbers):
prime_numbers.append(x)

print(prime_numbers)

[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547]

if you check the length of prime_numbers = 101
same as to print the results with index

for i,j in enumerate(prime_numbers):
print(i,j)

0 2
1 3
2 5
3 7
4 11
5 13
6 17
7 19
8 23
9 29
10 31
11 37
12 41
13 43
14 47
15 53
16 59
17 61
18 67
19 71
20 73
21 79
22 83
23 89
24 97
25 101
26 103
27 107
28 109
29 113
30 127
31 131
32 137
33 139
34 149
35 151
36 157
37 163
38 167
39 173
40 179
41 181
42 191
43 193
44 197
45 199
46 211
47 223
48 227
49 229
50 233
51 239
52 241
53 251
54 257
55 263
56 269
57 271
58 277
59 281
60 283
61 293
62 307
63 311
64 313
65 317
66 331
67 337
68 347
69 349
70 353
71 359
72 367
73 373
74 379
75 383
76 389
77 397
78 401
79 409
80 419
81 421
82 431
83 433
84 439

Answer 1

Your while condition is
counter_prime <= 100
So your loop has 101 iterations if counter_prime starts at 0.

Answer 2

but counter_prime is the length of list
length function start from 1 not 0