The cause, of this bug... is this string of code:

"### Terraforming Candidate
ship_event = {
id = anomaly.2575
title = "anomaly.2575.name"
desc = {
text = anomaly.2575.desc.1
trigger = {
NOT = {
owner = { has_technology = "tech_climate_restoration" }
solar_system = { has_star_flag = dyson_sphere_built }
}
}
}
desc = {
text = anomaly.2575.desc.2
trigger = {
owner = { has_technology = "tech_climate_restoration" }
NOT = {
solar_system = {
has_star_flag = dyson_sphere_built
}
}
}
}
desc = {
text = anomaly.2575.desc.3
trigger = {
solar_system = { has_star_flag = dyson_sphere_built }
}
}
picture = GFX_evt_drilling_for_gas
location = FROM

is_triggered_only = yes

option = {
name = FASCINATING
custom_tooltip = TERRAFORMING_CANDIDATE_EFFECT
hidden_effect = {
from = {
add_modifier = {
modifier = "terraforming_candidate"
days = -1
}
}
}
}
option = {
exclusive_trigger = {
solar_system = { has_star_flag = dyson_sphere_built }
}
name = UNFORTUNATE
owner = {
add_monthly_resource_mult = {
resource = society_research
value = @tier1researchreward
min = @tier1researchmin
max = @tier1researchmax
}
}
}
}
"

This string of code, is why you've been getting this bug. Go to C:\Program Files (x86)\Steam\steamapps\workshop\content\281990\2794211874\events, open anomaly_events_2.txt with Notepad++, and click the magnifying glass icon/"Find...". Then, type in "terraform" or "2575", without quotes, and click next. Then just highlight that entire string of code, and press delete or backspace. Make sure there is only one return/space separating the two surrounding strings of code.

There you go, the bug should be fixed. Dunno why the author of "Mergable Event Ships", added this string.